If anyone you know suffers from this, these are interesting articles. One is about giving babies these foods before the age of 6months, which is counter-intuitive from early advice to wait. They think that has caused the increase of allergies to nuts, shellfish and eggs. The second is about a study to de-sensitize older kids by gradually increasing their exposure. The third is about a patch that does something similar.

http://online.wsj.com/article/SB1000142 ... 96016.html

http://www.wbaltv.com/news/health/Study ... index.html

http://www.post-gazette.com/stories/new ... ne-688333/

FYI, my kids got a taste of peanut butter even before they started solid foods, lol. They got eggs as soon as they could handle them...very softly scrambled.
They never got shellfish, since we didn't eat them.